Transmission Lubricant Composition

ABSTRACT

A lubricant composition comprising a) a synthetic poly-alpha-olefin base fluid; b) an organomolybdenum friction modifier; c) an alkylphosphorothiolate and a hydrocarbylamine anti-wear combination; and d) a dihydrocarbyl dithiophosphate extreme pressure additive and optionally one or more of e) a copper corrosion inhibitor; f) an anti-foam agent; g) a solubilizing agent; h) polymeric viscosity index improver; and i) an oligomeric viscosity modifier is highly suitable for use in the synchronizer of a transmission.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/551,588, filed on Aug. 29, 2017. The contents of this application are hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to improved lubricants for transmissions with improved performance with metal synchromesh components.

BACKGROUND

Problems occur with synchronizer parts of transmissions with many oils delivering a non-optimal friction or which give rise to high wear of the components leading to synchromesh damage and poor or failed gears or bearings.

The synchronizer is one of the more important components of any gearbox. Increasing performance, reducing shift force and minimizing the between-the-gears energy losses are the primary objectives for synchronizer systems. Improvements in the capacity of the mechanical system and the introduction of various synchronizers of various designs and materials are allowing economical reengineering of existing synchronizer designs into more efficient designs. The lubricants and additives for transmission lubricating oils need to be reformulated for these designs to be able to maintain adequate friction between the interacting parts of the synchronizer and to protect these parts from wear.

Conventional gear oils or transmission oils do not adequately protect the lubricated surfaces from abrasive or corrosive wear.

SUMMARY

Accordingly, disclosed is a lubricant composition comprising a) a synthetic poly-alpha-olefin base fluid; b) an organomolybdenum friction modifier; c) an alkylphosphorothiolate and a hydrocarbylamine anti-wear combination; and d) a dihydrocarbyl dithiophosphate extreme pressure additive.

The lubricant composition may advantageously contain one or more of e) a copper corrosion inhibitor; f) an anti-foam agent; g) a solubilizing agent; h) polymeric viscosity index improver; and i) an oligomeric viscosity modifier.

Also disclosed is a method of lubricating a surface in the synchronizer of a transmission, the method comprising supplying thereto the lubricant composition.

DETAILED DESCRIPTION

Synthetic poly-alpha-olefins include Group IV poly-alpha-olefins (PAOs), including either lower viscosity or high viscosity fluids. Included are known PAO materials which typically comprise relatively low molecular weight hydrogenated polymers or oligomers of alphaolefins which include but are not limited to C₂ to about C₃₂ alphaolefins, for example C₈ to about C₁₆ alphaolefins, such as 1-octene, 1-decene, 1-dodecene and the like. Examples of poly-alpha-olefins are poly-1-octene, poly-1-decene and poly-1-dodecene, as well as dimers of higher olefins in the range of C₁₄ to C₁₈, which provide low viscosity base stocks. In some embodiments, synthetic poly-alpha-olefins include trimers and tetramers of 1-octene and/or 1-decene.

Low viscosity PAO fluids may be prepared via polymerization of an alphaolefin in the presence of a polymerization catalyst such as a Friedel-Crafts catalyst, including, for example, aluminum trichloride, boron trifluoride or complexes of boron trifluoride with water, alcohols such as ethanol, propanol or butanol, carboxylic acids or esters such as ethyl acetate or ethyl propionate. Methods are disclosed for example in U.S. Pat. Nos. 3,382,291; 3,742,082; 3,769,363; 3,876,720; 4,149,178; 4,239,930; 4,367,352; 4,413,156; 4,434,408; 4,910,355; 4,956,122; and 5,068,487.

In some embodiments, the synthetic base fluid is present from about 62 wt % (weight percent), about 63, about 64, about 65, about 66, about 67, about 68, about 69, about 70, about 71, about 72, about 73, about 74, about 75 or about 76 wt % to about 77, about 78, about 79, about 80, about 81, about 82, about 83, about 84, about 85, about 86, about 87 or about 88 wt %, based on the weight of the total composition.

Organomolybdenum friction modifiers include organomolybdenum dithiocarbamates, organomolybdenum dithiophosphates, molybdenum carboxylate salts, molybdenum-amine complexes, molybdenum amine/alcohol/amide complexes, molybdenum cluster compounds and molybdenum disulfide.

In certain embodiments, the organomolybdenum friction modifier is from about 0.2 wt % to about 1.0 wt % or from about 0.3 wt % to about 0.7, about 0.8 or about 0.9 wt %; for example from about 0.40 wt %, about 0.41, about 0.42, about 0.43, about 0.44, about 0.45, about 0.46, about 0.47, about 0.48, about 0.49, about 0.50 or about 0.51 wt % to about 0.52, about 0.53, about 0.54, about 0.55, about 0.56, about 0.57, about 0.58, about 0.59 or about 0.60 wt %, based on the total weight of the composition.

In some embodiments, the alkylphosphorothiolate is of formula

wherein R₁, R₂ and R₃ are each independently hydrocarbyl or hydrogen, wherein at least one of R₁, R₂ and R₃ are hydrocarbyl and X₁, X₂ and X₃ are independently oxygen or sulfur; for example where each of X₁, X₂ and X₃ are oxygen or each are sulfur or where two of X₁, X₂ and X₃ are oxygen and the other is sulfur or where two of X₁, X₂ and X₃ are sulfur and the other oxygen.

The hydrocarbylamine may be selected from the group consisting of alkylene diamines, for example N-hydrocarbyl trimethylene diamines, for example N-oleyl-trimethylene diamine, N-tallow-trimethylene diamine or N-coco-trimethylene diamine.

In some embodiments, the hydrocarbylamine is selected from the group consisting of primary hydrocarbylamines, for example C₄-C₃₀alkylamines or C₈-C₂₀alkylamines, for example n-hexylamine, n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine or n-octadecylamine.

In some embodiments, the alkylphosphorothiolate/hydrocarbylamine anti-wear additive is from about 0.2 wt % to about 1.0 wt % or from about 0.3 wt % to about 0.7, about 0.8 or about 0.9 wt %; for example from about 0.40 wt %, about 0.41, about 0.42, about 0.43, about 0.44, about 0.45, about 0.46, about 0.47, about 0.48, about 0.49, about 0.50 or about 0.51 wt % to about 0.52, about 0.53, about 0.54, about 0.55, about 0.56, about 0.57, about 0.58, about 0.59 or about 0.60 wt %, based on the total weight of the composition.

The wt/wt ratio of the alkylphosphorothiolate and hydrocarbylamine is for instance from about 1/9, about 1/8, about 1/7, about 1/6, about 1/5, about 1/4, about 1/3, about 1/2 or about 1/1 to about 2/1, about 3/1, about 4/1, about 5/1, about 6/1, about 7/1, about 8/1 or about 9/1.

In some embodiments, the dihydrocarbyl dithiophosphate is of formula

wherein R₄, R₅ and R₆ are each independently hydrocarbyl.

For instance, the dihydrocarbyl dithiophosphate is of formula

wherein R₅ and R₆ are independently C₃-C₁₈alkyl, C₅-C₁₂cycloalkyl, C₉-C₁₀bicycloalkylmethyl, C₉-C₁₀tricycloalkylmethyl, phenyl or C₇-C₂₄alkylphenyl, or R₅ and R₆ together bonded to the oxygen atoms are

and R₇ is hydrogen or methyl; for example where R₅ and R₆ are 2-methylpropyl and R₇ is methyl.

In certain embodiments, the dihydrocarbyl dithiophosphate extreme pressure additive is from about 0.2 to about 1.2 wt % or from about 0.3 wt % to about 0.8, about 0.9, about 1.0 or about 1.1 wt %; for example from about 0.50 wt %, about 0.51, about 0.52, about 0.53, about 0.54, about 0.55, about 0.56, about 0.57, about 0.58, about 0.59, about 0.60 or about 0.61 wt % to about 0.62, about 0.63, about 0.64, about 0.65, about 0.66, about 0.67, about 0.68, about 0.69 or about 0.70 wt %, based on the total weight of the composition.

Anti-wear additives and extreme pressure additives are disclosed for instance in U.S. Pat. No. 8,404,624 and U.S. Pub. 2005/0090410.

Copper corrosion inhibitors constitute another class of additives suitable for inclusion in the compositions of this invention. Such compounds include thiazoles, triazoles and thiadiazoles. Examples of such compounds include benzotriazole, tolyltriazole, octyltriazole, decyltriazole, dodecyltriazole, 2-mercapto benzothiazole, 2,5-dimercapto-1,3,4-thiadiazole, 2-mercapto-5-hydrocarbylthio-1,3,4-thiadiazoles, 2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazoles, 2,5-bis(hydrocarbylthio)-1,3,4-thiadiazoles, and 2,5-bis(hydrocarbyldithio)-1,3,4-thiadiazoles. For instance, 1,3,4-thiadiazoles are available as articles of commerce and also combinations of triazoles such as tolyltriazole with a 1,3,4-thiadiazole such as a 2,5-bis(alkyldithio)-1,3,4-thiadiazole or 2-alkyldithio-5-mercapto-1,3,4-thiadiazole. Materials of these types commercially available include COBRATEC TT-100 and HITEC 4313. The 1,3,4-thiadiazoles are generally synthesized from hydrazine and carbon disulfide by known procedures. See, for example, U.S. Pat. Nos. 2,765,289; 2,749,311; 2,760,933; 2,850,453; 2,910,439; 3,663,561; 3,862,798; and 3,840,549.

A copper corrosion inhibitor may be present, in certain embodiments, from about 0.10 wt % to about 0.60 wt % or from about 0.10 wt % to about 0.40 or about 0.50 wt %; for example from about 0.10 wt %, about 0.11, about 0.12, about 0.13, about 0.14, about 0.15, about 0.16, about 0.17, about 0.18, about 0.19 or about 0.20 wt % to about 0.21, about 0.22, about 0.23, about 0.24, about 0.25, about 0.26, about 0.27, about 0.28, about 0.29 or about 0.30 wt %, based on the total weight of the composition.

Anti-foam agents include silicone oils, silicone resins, silicon glycols and the like. In one embodiment of the present invention the anti-foam agent comprises a silicone oil. In some embodiments of the present invention, the anti-foam agent comprises hydrocarbons or a blend of silicone and hydrocarbons. In certain embodiments of the present invention, the anti-foam agent includes trace amount of silicon components such as silicone oils, silicone resins, silicon glycols and the like.

The silicone oil is not generally limited and may include any silicone oil known in the art that does not adversely affect the lubricating properties of the resulting lubricating oil composition. Suitable silicone oils may include any liquid polymerized siloxane comprising one or more organic groups (polyorganosiloxanes). Examples of suitable silicone oils include, but are not limited to, polyalkylsiloxanes (e.g., polydimethylsiloxane—PDMS), polyarylsiloxanes, polyalkoxysiloxanes, polyaryloxysiloxanes, fluorinated polysiloxanes (e.g., trifluoropropylmethylsilicone), combinations thereof, etc. Generally, silicone oils suitable for use in the present invention may have a kinematic viscosity at 25° C. of at least 0.5 mm/s (cSt), for example from about 0.5 to about 1,000,000 mm²/s (cSt) or from about 10,000 to about 600,000 mm²/s (cSt). Silicone oil may be present in an anti-foam agent in an amount in the range of from about 0.01 to more than 99 wt %, in an amount in the range of from about 1 to about 10 wt %, in an amount of up to 1 wt %, based on the total weight of the anti-foam agent, or completely absent from the anti-foam agent. Further, the concentration of silicone oil present in the lubricating oil composition may be in a range of from 0.1 to 500 ppm, from 1 to 100 ppm, or from 1 to 50 ppm, by weight.

Optionally, anti-foam agents may further comprise a solvent, such as a paraffinic mineral oil, naphthenic mineral oil, petroleum naphtha, aromatics, toluene, xylene, benzene, hexane, heptane, octane, dodecane, kerosene, etc. and combinations thereof. An anti-foam agent may be dispersed or dissolved in the solvent. An anti-foam agent may include a non-ionic surfactant.

In certain embodiments, the anti-foam agent may have a density of about 0.7 kg/L to about 0.9 kg/L at 20° C., a viscosity of less than about 30 mPas at 25° C., and a kinematic viscosity of less than about 20 mm²/s at 40° C. Exemplary anti-foam agents that may be used in the present invention include, without limitations, Foam Ban® 130B and Synative® AC AMH 2.

In certain embodiments, the lubricant composition may include a solvent in which the anti-foam compound(s) can be dispersed or dissolved.

In some embodiments, an anti-foam agent is present from about 0.10 wt % to about 1.20 wt % or from about 0.20 wt % to about 0.80, about 0.90, about 1.00 or about 1.10 wt %; for example from about 0.50 wt %, about 0.51, about 0.52, about 0.53, about 0.54, about 0.55, about 0.56, about 0.57 or about 0.58 to about 0.59, about 0.60 wt % to about 0.61, about 0.62, about 0.63, about 0.64, about 0.65, about 0.66, about 0.67, about 0.68, about 0.69 or about 0.70 wt %, based on the total weight of the composition.

In other embodiments, an anti-foam agent is present from about 0.20 wt %, about 0.21, about 0.22, about 0.23, about 0.24, about 0.25, about 0.26, about 0.27, about 0.28, about 0.29 or about 0.30 wt % to about 0.31, about 0.32, about 0.33, about 0.34, about 0.35, about 0.36, about 0.37, about 0.38, about 0.39, about 0.40, about 0.41, about 0.42, about 0.43, about 0.44, about 0.45, about 0.46, about 0.47, about 0.48 or about 0.49 wt %, based on the total weight of the composition.

In yet other embodiments, an anti-foam agent is present from about at up to 0.1 wt %, from about 0.01 wt % to about 0.1 wt %, or from about 0.02 wt % to about 0.06 wt %.

The present compositions may advantageously comprise a solubilizing agent, for example an oil-soluble di-alkyl ester of a C₄-C₁₄ or C₆-C₁₀ α,ω-di-carboxylic acid having a pour point of about −45° C. or lower, for example −55° C. or lower. For example, diesters including C₈-C₁₃ alkanol adipates, azelates, sebacates and mixtures thereof. Examples include tri-methylpropyl tricaprylate, di-isodecyl glutarate, di-isododecyl glutarate, di-isooctyl adipate, di-(2-ethylhexyl) adipate, di-isononyl adipate, di-isodecyl adipate, di-(tridecyl) adipate, di-propylheptyl adipate, di-propyladipate, di-(2-ethylhexyl) sebacate, di-isooctyl sebacate, di-octyl azelate, di-isooctyl azelate, di-(2-ethylhexyl) azelate, di-isooctyl dodecanediate and mixtures thereof. Mixtures of two or more different types of diesters (e.g., dialkyl adipates and dialkyl azelates, etc.) can also be used.

A solubilizing agent may be present for instance from about 1.0 wt % to about 9.0 wt % or from about 2.0 wt % or about 3.0 wt % to about 7.0 or about 8.0 wt %; for example from about 4.0 wt %, about 4.1, about 4.2, about 4.3, about 4.4, about 4.5, about 4.6, about 4.7, about 4.8, about 4.9 or about 5.0 wt % to about 5.1, about 5.2, about 5.3, about 5.4, about 5.5, about 5.6, about 5.7, about 5.8, about 5.9 or about 6.0 wt %, based on the total weight of the composition.

Polymeric viscosity index improvers include polyacrylates, polymethacrylates, vinylpyrrolidone/methacrylate copolymers, polyvinylpyrrolidones, polybutenes, olefin copolymers, styrene/acrylate copolymers and polyethers. Commercial polymeric viscosity index improvers include VISCOPLEX and ACRYLOID products.

A polymeric viscosity index improver may be present for example from about 1.0 wt % to about 9.0 wt % or from about 2.0 wt % or about 3.0 wt % to about 7.0 or about 8.0 wt %; for example from about 4.0 wt %, about 4.1, about 4.2, about 4.3, about 4.4, about 4.5, about 4.6, about 4.7, about 4.8, about 4.9 or about 5.0 wt % to about 5.1, about 5.2, about 5.3, about 5.4, about 5.5, about 5.6, about 5.7, about 5.8, about 5.9 or about 6.0 wt %, based on the total weight of the composition.

Oligomeric viscosity modifiers include olefin co-oligomers, for example ethylene co-alpha-olefin oligomers, for example ethylene-propylene co-oligomers. A commercially available co-oligomer is LUCANT HC 1100.

An oligomeric viscosity modifier may be present for instance from about 1.0 wt % to about 9.0 wt % or from about 2.0 wt % or about 3.0 wt % to about 7.0 or about 8.0 wt %; for example from about 4.0 wt %, about 4.1, about 4.2, about 4.3, about 4.4, about 4.5, about 4.6, about 4.7, about 4.8, about 4.9 or about 5.0 wt % to about 5.1, about 5.2, about 5.3, about 5.4, about 5.5, about 5.6, about 5.7, about 5.8, about 5.9 or about 6.0 wt %, based on the total weight of the composition.

Hydrocarbyl is any hydrocarbon containing group, for example aryl, alkaryl, straight or branched chain alkyl or alkenyl, cycloalkyl or cycloalkylalkyl which may be interrupted by or substituted by one or more heteroatom-containing groups or aryl groups, for instance interrupted by one or more, for example 1 to 3, —O—, —NH— or —C(O)O— groups and/or substituted by one or more, for example 1 to 3, halogen, hydroxyl, carboxylic, amino, thiol, phosphonate or aryl groups. Aryl includes phenyl and substituted phenyl, for instance alkyl-substituted phenyl. Hydrocarbyl may contain for instance from 1 to 150 carbon atoms.

The term “organo” is equivalent to “hydrocarbyl”.

Alkyl includes straight or branched 1 to 25 carbon atom chains, for example methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, icosyl and docosyl. Alkenyl groups are for instance unsaturated versions of alkyl groups.

Cycloalkyl is for example C₅-C₂cycloalkyl, e.g., cyclopentyl or cyclohexyl. Cycloalkylalkyl is for example C₅-C₂Cycloalkyl-C₁-C₄alkyl, e.g. cyclopentylmethyl, 2-cyclopentylethyl, cyclohexylmethyl or 2-cyclohexylethyl. Bi- or tri-cycloalkyl means for example bi-cyclohexylmethyl and the like.

Present composition may advantageously contain a further component selected from the group consisting of solvents, hindered phenolic antioxidants, aminic antioxidants, metal passivators, rust inhibitors, pour point depressants, dispersants, further anti-foam agents, demulsifiers, further friction modifiers, further anti-wear additives and mixtures thereof.

Present compositions may further include as further anti-wear additives, metal complex compounds of hydrocarbyl dithiophosphates of formula

wherein R and R′ are independently selected from the group consisting of C₁-C₂₀alkyl, C₃-C₂₀, C₅-C₁₂cycloalkyl, C₇-C₁₃aralkyl and C₆-C₁₀aryl, M is a metal selected from the group consisting of Al, Pb, Sn, Mn, Co, Ni, Zn and Cu, x is 2 or 3 and y is 1 or 2. A suitable dihydrocarbyl dithiophosphate is for instance zinc dialkyldithiophosphate.

Solvents include paraffinic mineral oil, naphthenic mineral oil, petroleum naphtha, aromatics, toluene, xylene, benzene, hexane, heptane, octane, dodecane, kerosene, etc. and combinations thereof.

Phenolic antioxidants that may be used include C₇-C₉ branched alkyl esters of 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-benzenepropanoic acid, 2-t-butylphenol, 2-t-butyl-4-methylphenol, 2-t-butyl-5-methylphenol, 2,4-di-t-butylphenol, 2,4-dimethyl-6-t-butylphenol, 2-t-butyl-4-methoxyphenol, 3-t-butyl-4-methoxyphenol, 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-4-alkylphenols such as 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol and 2,6-di-t-butyl-4-ethylphenol, 2,6-di-t-butyl-4-alkoxyphenols such as 2,6-di-t-butyl-4-methoxyphenol and 2,6-di-t-butyl-4-ethoxyphenol, 3,5-di-t-butyl-4-hydroxybenzylmercaptooctylacetate, alkyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionates such as n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, n-butyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate and 2′-ethylhexyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,6-d-t-butyl-α-dimethylamino-p-cresol, 2,2′-methylene-bis(4-alkyl-6-t-butylphenol) such as 2,2′-methylenebis(4-methyl-6-t-butylphenol, and 2,2-methylenebis(4-ethyl-6-t-butylphenol), bisphenols such as 4,4′-butylidenebis(3-methyl-6-t-butylphenol, 4,4′-methylenebis(2,6-di-t-butylphenol), 4,4′-bis(2,6-di-t-butylphenol), 2,2-(di-p-hydroxyphenyl)propane, 2,2-bis(3,5-di-t-butyl-4-hydroxyphenyl)propane, 4,4′-cyclohexylidenebis(2,6-t-butylphenol), hexamethyleneglycol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], triethyleneglycolbis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], 2,2′-thio-[diethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 3,9-bis{1,1-dimethyl-2-[3-(3-t-butyl-4-hydroxy-5-methyl-phenyl)propionyloxy]ethyl}2,4,8,10-tetraoxaspiro[5,5]undecane, 4,4′-thiobis(3-methyl-6-t-butylphenol) and 2,2′-thiobis(4,6-di-t-butylresorcinol), polyphenols such as tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, bis-[3,3′-bis(4′-hydroxy-3′-t-butylphenyl)butyric acid]glycol ester, 2-(3′,5′-di-t-butyl-4-hydroxyphenyl)methyl-4-(2″,4″-di-t-butyl-3″-hydroxyphenyl)methyl-6-t-butylphenol and 2,6-bis(2′-hydroxy-3′-t-butyl-5′-methylbenzyl)-4-methylphenol, and p-t-butylphenol—formaldehyde condensates and p-t-butylphenol—acetaldehyde condensates.

Aminic antioxidants which may be conveniently used include alkylated diphenylamines, phenyl-α-naphthylamines, phenyl-β-naphthylamines and alkylated α-naphthylamines.

Exemplary aminic antioxidants include dialkyldiphenylamines, such as p,p′-dioctyl-diphenylamine, p,p′-di-α-methylbenzyl-diphenylamine, and N-p-butylphenyl-N-p′-octylphenylamine, monoalkyldiphenylamines, such as mono-t-butyldiphenylamine and mono-octyldiphenylamine, bis(dialkylphenyl)amines, such as di-(2,4-diethylphenyl)amine and di(2-ethyl-4-nonylphenyl)amine, alkylphenyl-1-naphthylamines, such as octylphenyl-1-naphthylamine and n-t-dodecylphenyl-1-naphthylamine, 1-naphthylamine, arylnaphthylamines, such as phenyl-1-naphthylamine, phenyl-2-naphthylamine, N-hexylphenyl-2-naphthylamine and N-octylphenyl-2-naphthylamine, phenylenediamines, such as N,N′-diisopropyl-p-phenylenediamine and N,N′-diphenyl-p-phenylenediamine, and phenothiazines, such as phenothiazine and 3,7-dioctylphenothiazine.

Examples of rust inhibitors include 1) organic acids, their esters, metal salts, amine salts and anhydrides, for example alkyl- and alkenylsuccinic acids and the partial esters thereof with alcohols, diols or hydroxycarboxylic acids, partial amides of alkyl- and alkenylsuccinic acids, 4-nonylphenoxyacetic acid, alkoxy- and alkoxyethoxycarboxylic acids, such as dodecyloxyacetic acid, dodecyloxy(ethoxy)acetic acid and the amine salts thereof, and also N-oleoylsarcosine, sorbitan monooleate, lead naphthenate, alkenylsuccinic anhydrides, for example dodecenylsuccinic anhydride, 2-(2-carboxyethyl)-1-dodecyl-3-methylglycerine and its salts, for instance sodium and triethanolamine salts; 2) nitrogen-containing compounds, for example: i) primary, secondary or tertiary aliphatic or cycloaliphatic amines and amine salts of organic and inorganic acids, for example oil-soluble alkylammonium carboxylates, and also 1-(N,N-bis(2-hydroxyethyl)amino)-3-(4-nonylphenoxy)propan-2-ol; ii) heterocyclic compounds, for example: substituted imidazolines and oxazolines, 2-heptadecenyl-1-(2-hydroxyethyl)-imidazoline; 3) phosphorus-containing compounds, for example Amine salts of phosphoric acid partial esters or phosphonic acid partial esters, zinc dialkyldithiophosphates; 4) sulfur-containing compounds, for example: barium dinonylnaphthalene-sulfonates, calcium petroleumsulfonates, alkylthio-substituted aliphatic carboxylic acids, esters of aliphatic 2-sulfocarboxylic acids and salts thereof; and 5) glycerine derivatives, for example: glycerine monooleate, 1-(alkylphenoxy)-3-(2-hydroxyethyl)glycerines, 1-(alkylphenoxy)-3-(2,3-dihydroxypropyl)glycerines, 2-carboxyalkyl-1,3-dialkylglycerines.

Pour point depressants include alkylated naphthalene derivatives.

Dispersants/surfactants include polybutenylsuccinamides or -imides, polybutenylphosphonic acid derivatives and basic magnesium, calcium and barium sulfonates, phenolates and salicylates.

Further anti-foam agents include alcohol ethoxy/propoxylates, fatty acid ethoxy/propoxylate, sorbitan partial fatty acid esters, and the like.

Demulsifiers include polyetherpolyols and dinonylnaphthalenesulfonates.

Further friction modifiers include fatty acids and their derivatives (i.e. natural esters of fatty acids such as glycerol monooleate), amides, imides and amines (i.e. oleylamine, diisotridecylamine).

Additional anti-wear additives include sulfur- and/or phosphorus- and/or halogen-containing compounds, such as sulfurized olefins and vegetable oils, tritolyl phosphate, tricresyl phosphate, chlorinated paraffins, alkyl and aryl di- and trisulfides, amine salts of mono- and dialkyl phosphates, amine salts of methylphosphonic acid, diethanolaminomethyltolyltriazole, di-(2-ethylhexyl)-aminomethyltolyltriazole, derivatives of 2,5-dimercapto-1,3,4-thiadiazole, ethyl(bisisopropyloxyphosphinothioyl)thiopropionate, triphenyl thiophosphate (triphenyl phosphorothioate), tris(alkylphenyl) phosphorothioates and mixtures thereof (for example tris(isononylphenyl) phosphorothioate), diphenylmonononylphenyl phosphorothioate, isobutylphenyl diphenyl phosphorothioate, the dodecylamine salt of 3-hydroxy-1,3-thiaphosphetan 3-oxide, trithiophosphoric acid 5,5,5-tris-isooctyl 2-acetate, derivatives of 2-mercaptobenzothiazole, such as 1-N,N-bis(2-ethylhexyl)aminomethyl-2-mercapto-1H-1,3-benzothiazole and ethoxycarbonyl 5-octyldithiocarbamate.

In some embodiments, a further component may be present up to about 21 wt %, up to about 15 wt %, up to about 10 wt %, up to about 5 wt %, up to about 1 wt %, from about 0.0 wt % to about 0.9 wt % or from about 0.1 wt % to about 21 wt %, based on the total weight of the composition; for example from about 1 wt %, about 2, about 3, about 4, about 5, about 6, about 7 or about 8 wt % to about 9, about 10, about 15, about 18, about 19, about 20 or about 21 wt %, based on the total weight of the composition. In some embodiments, the further component may be present from about 0.1 wt % to about 1.2 wt % or from about 0.2 wt %, about 0.3 wt %, about 0.4 wt %, or about 0.5 wt % to about 0.6 wt %, about 0.7 wt %, about 0.8 wt %, about 0.9 wt %, about 1 wt %, or about 1.1 wt %.

The present lubricant compositions may advantageously exhibit a kinematic viscosity of from about 9.0 mm²/s, about 9.5, about 10.0, about 10.5, about 11.0 or about 11.5 mm²/s to about 12.0 mm²/s, about 12.5, about 13.0, about 13.5, about 14.0, about 14.5 or about 15.0 mm²/s at 100° C., determined according to ASTM D445; for example from about 10.0 mm²/s to about 14.5 mm²/s , from about 11.0 mm²/s to about 13.5 mm²/s or from about 11.5 mm²/s to about 12.5 mm²/s at 100° C., determined according to ASTM D445. Alternatively, the lubricant compositions may exhibit a kinematic viscosity of from about 7 to about 11.5 mm²/s at 100° C.; or from about 8 to about 10.5 mm²/s at 100° C. or from about 9 to about 9.5 mm²/s at 100° C., determined according to ASTM D445.

The present lubricant compositions may advantageously exhibit a dynamic viscosity of from about 10,000 mPa*s, about 15,000, about 20,000, about 25,000, or about 30,000 mPa*s to about 35,000 mPa*s, about 40,000, about 45,000, about 50,000, about 55,000, about 60,000, about 65,000, about 70,000, or about 75,000 mPa*s at −40 ° C., determined according to DIN51398.

The present lubricant compositions may exhibit a density ranging from about 820 kg/m³, about 830, about 840, about 850 kg/m³ to about 860 kg/m³, about 870, about 880, about 890, or about 900 kg/m³ at 15° C., determined according to ASTM D4052.

The phosphorus content in the present lubricant compositions may range from about 500 ppm, about 600, about 700, about 800, or about 900 ppm to about 1000 ppm, about 1100, about 1200, about 1300, about 1400, or about 1500 ppm, determined according to ASTM 5185.

The sulfur content in the present lubricant compositions may range from about 5000 ppm, about 6000, about 7000, about 8000, about 9000, about 9500, about 9800 ppm to about 10000 ppm, about 10500, about 11000, about 11500, about 12000, about 12500, about 13000, about 14000, or about 15000 ppm, determined according to ASTM 5185.

A synchronizer may comprise a surface selected from the group consisting of molybdenum, bronze, brass, iron, carbon and steel, for example sintered bronze.

The total weight of the lubricant composition will be 100% and the components of the composition are adjusted to where the total composition is 100% by weight. Unless otherwise indicated, all parts and percentages are by weight.

A vehicle is a passenger automobile, a truck, a sport utility vehicle, a construction vehicle, a van, a step van, a minivan, a jeep, a farm vehicle including a tractor, a military vehicle, a light duty truck, etc.

EXAMPLES

The following examples are set forth to assist in understanding the invention and should not be construed as specifically limiting the invention described and claimed herein. Such variations of the invention, including the substitution of all equivalents now known or later developed, which would be within the purview of those skilled in the art, and changes in formulation or minor changes in experimental design, are to be considered to fall within the scope of the invention incorporated herein.

Example 1—Lubricant Composition and its Method of Preparation

TABLE 1 Lubricant Composition Component Amount (wt %) Synthetic poly-alpha-olefin base fluid 66-84 Organomolybdenum friction modifier 0.4-0.6 Alkylphosphorothiolate and hydrocarbylamine 0.4-0.6 anti-wear additive combination Dihydrocarbyl dithiophosphate extreme 0.5-0.7 pressure additive Copper corrosion inhibitor 0.1-0.3 Anti-foam agent 0.5-0.7 A solubilizing agent 4-6 A polymeric viscosity index improver 4-6 An oligomeric viscosity modifier 4-6 A friction modifier 0.0-0.9 A further component 0.1-21 

The lubricant composition of Table 1 may be prepared by:

(B1) pre-blending part of the solubilizing agent with the organomolybdenum friction modifier and stirring at ambient temperature in a stirred vessel;

(B2) charging the synthetic poly-alpha-olefin base fluid into a blending vessel and heating to about 35-55° C. while stirring followed by addition of a polymeric viscosity index improver and the oligomeric viscosity modifier and stirring until the viscosity index improver and viscosity modifier are fully dissolved;

(B3) charging to the blending vessel the friction modifier, dihydrocarbyl dithiophosphate extreme pressure additive, further component(s), alkylphosphorothiolate and hydrocarbylamine anti-wear additive combination, and the copper corrosion inhibitor and stirring for about 10 minutes to about 1 hour at about 35-55° C.;

(B4) charging the pre-blend from (B1) to the blending vessel and adding the remaining portion of the solubilizing agent;

(B5) cooling the composition in the blending vessel to up to about 35° C., adding the anti-foam agent and stir for about 10 minutes to about 1 hour.

It should be understood that the composition of Table 1 and the corresponding blending procedure are merely illustrative and should not be construed as limiting.

Example 2—Compatibility Test of Lubricant Composition with Sintered Bronze Friction Material

The compatibility of the lubricant composition of Example 1 with a synchronizer surface made from sintered bronze was evaluated by testing the friction and endurance behavior of the lubricant composition using the Standard Synchronizer Test rig ZF/ZFG SSP 180 at a high oil temperature of about 120° C. Daimler's double cone synchronizer DK-140 with sintered bronze (HS45) friction material was used. The test was run for 288,935 cycles before a failure was observed (in repetitions of this test, the number of cycles varied between about 242,000 and about 289,000 cycles). The minimum coefficient of friction at the end of the test was μ_(min)=0.070. The axial wear was rather high. The thermal stability of the lubricant composition was good and demonstrated only little deposition of oil components on the test parts.

Example 3—Compatibility Test of Lubricant Composition with Molybdenum Friction Material

The compatibility of the lubricant composition of Example 1 with a synchronizer surface made from molybdenum was evaluated by testing the occurrence of scuffing and coefficient of friction using the Standard Synchronizer Test rig ZF/ZFG SSP 180 at a high oil temperature of about 80° C.

Daimler's synchronizer AK-180 with molybdenum (Mo) friction material was used. The test was run for the complete 13,000 cycles. Scuffing occurred for the first time in the main-load stage with pressure p=1.94 N/mm². The number of cycles with scuffing in the main load stage is low and in the following two main-load stages is very low. The average coefficient of friction at the end of the test was μ_(avg)=0.070.

There is a need in the art for a lubricant composition that is compatible with various synchronizer friction materials while at the same time passing all other requirements of the Daimler specification for heavy duty truck manual transmission per specification 235.16. The lubricant composition disclosed herein addresses this need by demonstrating good compatibility with various synchronizer friction materials (e.g., bronze and molybdenum) and passing all other requirements of the Daimler specification for heavy duty manual transmissions per specification 235.16.

The articles “a” and “an” herein refer to one or to more than one (e.g. at least one) of the grammatical object. Any ranges cited herein are inclusive. The term “about” used throughout is used to describe and account for small fluctuations.

The term “about” may mean the numeric value may be modified by ±5%, ±4%, ±3%, ±2%, ±1%, ±0.5%, ±0.4%, ±0.3%, ±0.2%, ±0.1% or ±0.05%. All numeric values are modified by the term “about” whether or not explicitly indicated. Numeric values modified by the term “about” include the identified value; that is “about 5.0” includes 5.0. Measureable levels of atoms, elements or molecules may depend on the method of detection. In part, the term “about” is intended to provide for this.

U.S. patents and published U.S. patent applications listed herein are hereby incorporated by reference. 

1. A lubricant composition comprising a) a synthetic poly-alpha-olefin base fluid; b) an organomolybdenum friction modifier; c) an alkylphosphorothiolate and a hydrocarbylamine anti-wear combination; and d) a dihydrocarbyl dithiophosphate extreme pressure additive.
 2. The lubricant composition according to claim 1 comprising a synthetic poly-alpha-olefin base fluid selected from the group consisting of about C₈ to about C₁₆ poly-alpha-olefins.
 3. (canceled)
 4. The lubricant composition according to claim 1 comprising a friction modifier selected from the group consisting of organomolybdenum dithiocarbamates, organomolybdenum dithiophosphates, molybdenum carboxylate salts, molybdenum-amine complexes, molybdenum amine/alcohol/amide complexes, molybdenum cluster compounds and molybdenum disulfide.
 5. (canceled)
 6. The lubricant composition according to claim 1 comprising an alkylphosphorothiolate of formula

wherein R₁, R₂ and R₃ are each independently hydrocarbyl or hydrogen, wherein at least one of R₁, R₂ and R₃ are hydrocarbyl and X₁, X₂ and X₃ are independently oxygen or sulfur.
 7. The lubricant composition according to claim 1 comprising a hydrocarbylamine selected from the group consisting of alkylene diamines, primary hydrocarbylamines, and a combination thereof.
 8. (canceled)
 9. The lubricant composition according to claim 1, wherein the wt/wt ratio of the alkylphosphorothiolate and hydrocarbylamine is from about 1/9 to about 9/1.
 10. The lubricant composition according to claim 1 comprising a dihydrocarbyl dithiophosphate of formula

wherein R₄, R₅ and R₆ are each independently hydrocarbyl.
 11. (canceled)
 12. The lubricant composition according to claim 1 having a kinematic viscosity of from about 9.0 mm²/s to about 15.0 mm²/s at 100° C., determined according to ASTM D445.
 13. The lubricant composition according to claim 1 wherein the synthetic base fluid is from about 62 wt % (weight percent to about 88 wt %, based on the weight of the total composition.
 14. The lubricant composition according to claim 1 wherein the organomolybdenum friction modifier is from about 0.2 wt % to about 1.0 wt %, based on the total weight of the composition.
 15. The lubricant composition according to claim wherein the anti-wear combination is from about 0.2 wt % to about 1.0 wt %, based on the total weight of the composition.
 16. The lubricant composition according to claim wherein the dihydrocarbyl dithiophosphate extreme pressure additive is from about 0.2 to about 1.2 wt %, based on the total weight of the composition.
 17. (canceled)
 18. The lubricant composition according to claim 1 further comprising: a copper corrosion inhibitor from about 0.10 wt % to about 0.60 wt %, based on the total weight of the composition, an anti-foam agent from about 0.10 wt % to about 1.20 wt %, based on the total weight of the lubricant composition, a solubilizing agent from about 1.0 wt % to about 9.0 wt %, based on the total weight of the lubricant composition, a polymeric viscosity index improver from about 1.0 wt % to about 9.0 wt %, based on the total weight of the lubricant composition, an oligomeric viscosity modifier from about 1.0 wt % to about 9.0 wt %, based on the total weight of the lubricant composition, and a further component selected from the group consisting of solvents, hindered phenolic antioxidants, aminic antioxidants, metal passivators, rust inhibitors, pour point depressants, dispersants, further anti-foam agents, demulsifiers, further friction modifiers, further anti-wear additives, detergents and mixtures thereof. 19.-36. (canceled)
 37. A lubricant composition comprising ) a synthetic poly-alpha-olefin base fluid; b) an organomolybdenum friction modifier; c) an alkylphosphorothiolate and hydrocarbylamine anti-wear additive combination; d) a dihydrocarbyl dithiophosphate extreme pressure additive; and e) a copper corrosion inhibitor; and/or f) an anti-foam agent; and/or g) a solubilizing agent; and/or h) a polymeric viscosity index improver; and/or i) an oligomeric viscosity modifier; and/or j) a further component. 38.-40. (canceled)
 41. A method of lubricating a surface in the synchronizer of a transmission, the method comprising supplying thereto a lubricant composition according to claim
 1. 42. A method according to claim 41, wherein the synchronizer comprises a surface selected from the group consisting of molybdenum, bronze, brass, iron, carbon and steel.
 43. A transmission comprising the lubricant composition according to claim
 1. 44. A gear box comprising the lubricant composition according to claim
 1. 45. A vehicle comprising the lubricant composition according to claim
 1. 46. A vehicle comprising a transmission comprising the lubricant composition according to claim
 1. 